February 18, 2012 : Engineers from HCC's Water Solutions vertical, who are constructing the 12.24 km long, 3.60 m diameter underground water tunnel from Marol Maroshi to Ruparel College (in Mumbai city), achieved a major breakthrough on February 18, 2012 - by daylighting the section of the tunnel near Ruparel College in Matunga. This marks the completion of the tunnel excavation and boring phase of one of Mumbai's longest and biggest underground water tunnels.

The tunnel stretch is divided into three sections namely, Maroshi-Vakola (5.83 km long), Vakola-Mahim (4.55 km long) and Mahim-Ruparel College (1.86 km long). Daylighting of the Maroshi-Vakola section was achieved in October 2009, while daylighting of the Vakola-Mahim section was completed in February 2011.

An interesting aspect of the project is that it runs under the Mahim creek, the Western Railway tracks, the Mithi River near Bandra Kurla Complex and beneath the Mumbai Airport's runways at a depth of around 70-80 meters below the ground level. Even as hundreds of trains, flights and vehicles used the tracks, runways and roads above, HCC's engineers have been steadily at work on this project over the last five years, using two tunnel boring machines, and excavating an average of 16 m per day.

Enhancing Mumbai's water lifelines
This project is part of the rehabilitation and improvement of the water supply and distribution system undertaken by the Brihanmumbai Municipal Corporation (BMC). This tunnel is connected with shafts at Maroshi, Vakola, Mahim and Ruparel College locations. The shafts are 12 m in diameter and about 70 m deep which is equivalent to a 20-storey building. The HCC project team is currently engaged in completing the concrete lining and pipeline works to connect the shafts to the water distribution networks of BMC. This tunnel will ensure uninterrupted water supply to the western suburbs and south-west part of Mumbai. The project is scheduled to be completed by September 2013.

Kudos to the Maroshi-Ruparel water tunnel project team for this outstanding engineering accomplishment.

Image caption :
HCC's engineers emerge after the successful daylighting of the final stage of the Maroshi-Ruparel tunnel project in Mumbai. In the background is the Tunnel Boring Machine (TBM) used for constructing the 3.60 m diameter tunnel